The fern is believed earth's oldest plant
BY JOE DANIEL SPECIAL CONTRIBUTOR

Ferns have been favored ornamental plants for generations. One of this country's forefathers, Thomas Jefferson, wrote about the ferns he observed in France in 1785. "Ferns are numerous. There are climbing ferns, water ferns, flowering ferns and tree ferns." His enthusiasm for ferns is obvious but we have to question the flowering fern. Botanically the fern plant is a sporophyte and neither forms flowers or seed. In the nursery industry, it is not uncommon to have plants outside of the four most common families called ferns. Fossil remains indicate they are some of earth's oldest plants. Just the sight of a tree fern makes you want to look for dinosaurs tracks. Even though there are more than 10,000 fern species, it is the Boston fern that most gardeners picture when they hear the word fern. Here are some hints on growing Boston ferns.

The Boston fern is a cultivar of the sword fern, Nephrolepis exaltata. The species is native to the American tropics and subtropics but the cultivar got its name in 1894 from the U. S. City near the latitude of 42 degrees north in Massachusetts. As fiction could have never imagined, a grower in Philadelphia selected and propagated the mutation that became known as Nephrolepis exaltata CV. Bostoniensis, or Boston fern. It is reported that a distributor in Boston sold 50,000 of them that year. In 1914, the massive central Florida foliage plant industry began with the Boston fern.

Knowing the optimum range for light, media pH and temperature is 5 percent of success with ferns. Most of the other 50 percent is not trying to stimulate growth when the plant is stressed.

Boston ferns can live through a fairly wide range of temperatures. However, night and day temperatures between 72 and 74 degrees Fahrenheit will give the most rapid growth. Fern baskets on the front porch seems to shout, "Look here, special care is given at this house." When day or night temperatures rise above 80 degrees the number of fronds per plant is reduced. It is the average daily temperature that is most important.

Media pH has a dramatic effect on fern growth. A pH range from 4.8 to 5.8 is considered optimum for most cultivars. Growing with a pH from 6.2 to 7 reduces the growth rate by 25 to 50 percent. High alkalinity water can raise media pH to a problem level. This is usually controlled by acidification of the water, reducing the limestone in the media or using an acid forming fertilizers.

Both light intensity and photoperiod are critical for good Boston ferns. During an East Texas winter when daylight hours are less than 10, fronds will be short. Winter frond length can be increased with four hours of night interruption from 10 p.m. to 2 a.m. with 10 footcandles intensity. The light intensity level considered optimum is from 2,000 to 4,000 footcandles. About 50 percent shade is needed in the East Texas summer.

Ferns are often stressed in East Texas since most of our days are hotter and brighter than optimum. Ferns are easily over watered when stressed and grown in a poorly drained pot. One can prevent this problem by drenching ferns thoroughly when the media is dry and the leaves begin to become translucent.

Despite less than optimum growing conditions hundreds of thousands of Boston ferns are grown and enjoyed each year. By knowing and trying to provide as close to optimum as practical your ferns will be even more attractive.